chapter 2 the tools of psychological research · pdf filepsychology, fifth edition, james s....

Psychology, Fifth Edition, James S. Nairne

Chapter 2

Chapter 2

The Tools of Psychological Research


Chapter 2

The Scientific Method

• Recall: Psychology is the scientific study of

behavior and mind

• Four main steps of scientific investigation:

– Observe

– Detect Regularities

– Generate Hypothesis

– Observe

• Also need operational definitions: specify

concepts in terms of measurements


Chapter 2


Chapter 2

What’s It For? Unlocking the Secrets of

Behavior and Mind

• Goals of psychological research:

– observing and describing behavior

– predicting behavior

– explaining behavior

– treating participants ethically


Chapter 2

Descriptive Research: Learning Goals

1. Describe the techniques and goals of

descriptive research.

2. Explain how psychologists conduct

naturalistic research.

3. Discuss the gains and costs of case studies

and surveys.

4. Explain how statistics can summarize and

help interpret data.

5. Describe the purpose of psychological tests.


Chapter 2

Goals of Descriptive Research

• Goal: Observe and describe behavior

– Not: Explain causes (we’ll get to that later!)

• Concerns:

– Reactivity

• Did individuals change their normal

behavior because they were being

observed?

– External validity

• Do your observations apply to real life?


Chapter 2

Naturalistic Observation:

Focusing on Real Life• Record naturally occurring behavior in real-

life situation (not a laboratory)

– E.g.: children playing at a day care center

• Can reduce reactivity by

– Participant observation

– Measuring behavior indirectly

• Can verify external validity of experimental research

• Does not allow determination of cause and effect


Chapter 2


Chapter 2

Case Studies: Focusing on an Individual

• Focus on a single case, usually an individual

– Usually involves gathering a lot of information on background, behavior of that individual

• Excellent for generating hypotheses

• Potential problems:

– External validity: Is that one individual representative?

– Verification: Is that one individual being truthful?


Chapter 2

Surveys: Focusing on the Group

• Gather a limited amount of information from

many people

– Often, but not always, in the form of a

questionnaire


– Obtaining a representative sample of

participants

– Can’t obtain in-depth information

– Are respondents’ answers accurate?


Chapter 2

Sampling From a Population

• Population: The group the researcher wants

to learn about

– Example: United States residents

• Sample: The subset of the population who

participates in the survey

• Random sampling: Everyone in population

has an equal chance of being selected

– Often difficult, but best for ensuring a

representative sample


Chapter 2

Psychological Tests: Assessing Individual

Differences• Achievement tests: Measure current level of

knowledge or competence in a subject

• Aptitude tests: Measure potential for success

in given profession or area of study

• Intelligence and personality tests: Measure

ability, or an individual’s tendency to act in

certain ways


Chapter 2

Statistics: Summarizing and Interpreting the

Data• Research projects yield observations (data);

researchers attempt to draw conclusions

based on the data


– How can you avoid introducing own

biases?

– How do you generalize your findings to a

larger population?


Chapter 2

Measures of Central Tendency

• Summarizes observations in a single

representative number around which scores

cluster

– Mean: Arithmetic average of set of scores

– Mode: Most frequently occurring score in

set

– Median: Middle point in set of scores

• Median, mode less affected by extreme

scores than the mean is


Chapter 2


Chapter 2

Variability

• Variability: How much the scores in a set differ from one another

– Example: Two classes might have the same average exam score, but one set of scores might be much more spread out

• Range: Difference between the lowest score and the highest score

• Standard deviation: Average distance of scores from the mean


Chapter 2


Chapter 2

Inferential Statistics

• Help researchers to decide

– whether a sample is representative of a population

– the likelihood that results are due to chance

– Example: Does a gender difference in scores mean there’s a “real” gender difference, or is the difference due to chance?

• Statistical significance: probability that outcome due to chance is less than .05.


Chapter 2

Predicting Behavior: Correlational Research

Learning Goals1. Define correlation and explain how

correlations can be used to predict behavior.

2. Explain why correlations cannot normally be

used to determine the cause of behavior.


Chapter 2

Correlational Research

• Correlation coefficient used to summarize

whether two measures vary together

– Positive correlation: One measure goes up,

the other tends to go up as well

– Negative correlation: One measure goes

up, the other tends to go down

– Zero correlation: Knowing value of one

measure does not allow you to predict

value of the other measure


Chapter 2

Correlation Coefficients

• Range from -1.00 to +1.00

• Absolute value: strength of relationship

– Closer to |1.00|: stronger relationship,

better able to predict one variable from the

other

• Sign: direction of relationship, positive or

negative


Chapter 2


Chapter 2

Correlations and Causality

• Measures may be correlated, but that doesn’t

mean one caused the other

– Example: Does watching violent television

cause a child to become aggressive?

• Third variables: A common link that could

explain the correlation

– Example: Perhaps certain kinds of parents

allow violent television and encourage

aggression


Chapter 2

Experimental Research: Learning Goals

1. Explain how and why experiments are

conducted.

2. Discuss the difference between independent

and dependent variables.

3. Explain what is meant by experimental

control, how it allows for determination of

causality.


Chapter 2

Learning Goals, continued…

4. Describe the problems created by

expectancies and biases and how these

problems are solved.

5. Discuss the problems associated with

generalizing experimental conclusions.


Chapter 2

Experimental Research: How and Why

• Experimenters actively manipulate

environment in order to observe effect on

behavior

– Example: Deliberately expose one group of

children to violent show, another group to

nonviolent show, and observe behavior of

each group

• Differs from simply recording, observing

behavior: Manipulating allows determination

of causality


Chapter 2

Variables

• Independent variable: Aspect of the environment that is manipulated or changed

– Must involve at least two conditions

• Example: Violent show / nonviolent show

• Dependent variable: Behavior that is measured or observed

– Example: Aggressive behavior. Hypothesis tested by observing effect of manipulating independent variable


Chapter 2

Experimental Control and Causality

• Experimental and control groups must be similar except with regard to independent variable

• There must be no confounding variables

– Confounding variables: Uncontrolled variables that change systematically with the independent variable

– Internal validity: confounding variables controlled

• Random assignment: Each participant has equal chance of ending up in any group


Chapter 2


Chapter 2

Experimental Research: An Illustration

• Does marijuana impair

memory? In this brief

description of a research

project, the answer is yes.


Chapter 2

PLAY VIDEO

Does Marijuana Impair Memory?


Chapter 2

Expectancies and Biases

• Participants may guess what the researcher

expects to find, change behavior accordingly

• Ways of reducing expectancy effects:

– Mislead about the purpose of the study

– Equate expectations for the experimental

and control groups

• Give placebo to control group

• Single-blind studies

• Double-blind studies


Chapter 2

Generalizing Experimental Conclusions

• Must consider: Would participants have behaved the same way outside of the artificial laboratory situation?

– Example: Would children in the television study behave the same way at home or school?

• External validity: Do the results generalize to real-world situations?

– Note: Many “lab” findings do appear to be externally valid


Chapter 2

Ethical Principles of Psychological

Research: Learning Goals

1. Explain the principle of informed consent.

2. Discuss the roles of debriefing and

confidentiality in research.

3. Discuss the ethical issues involved in animal

research.


Chapter 2

Informed Consent

• Process of gaining permission and providing

explanation of:

– Any risks (physical or emotional) or other

factors that might affect decision to

participate

– What procedures are involved

• Participant must given written consent

• Participant may stop without penalty


Chapter 2

Deception in Research

• May be necessary to guard against reactivity

and expectancy

• Only justified if scientific, educational, or

applied value is clear, and if there is no other

way to answer research question

• Should not cause physical or emotional harm,

or affect willingness to participate


Chapter 2

Debriefing and Confidentiality

• Debriefing: After the experimental session is

over, telling participant more about the true

purpose

– Explain any deception that took place

• Confidentiality: Researcher does not discuss

personal information obtained from the

research without permission


Chapter 2

Ethics of Animal Research

• Benefits of animal research:

– Increases experimental control

– Increases range of possible projects

• Ethical issues in animal research:

– Informed consent can’t be obtained

– May involve injury or death to the animal

• Ethical guidelines:

– Care for animals properly

– Minimize pain and discomfort

chapter 2 the tools of psychological research · pdf filepsychology, fifth edition, james s....

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